Our major long-term objective is to understand the synaptic connections of the neurons of the human retina that underlie specific visual functions. An understanding of the neural pathways in the normal human retina will give us a basis on which to investigate abnormalities when a disease process has caused loss of,k or compromise to, any of the neurons of the retina. Using anatomical techniques of studying serial ultrathin sections and reconstructing neurons and portions of neuropil, we wish to understand: 1) how the chromatic pathways are constructed to achieve the midget ganglion cell single color opponent channels. This will involve determining what spectral types of cones have input to horizontal cells and whether narrow-field amacrine cells have special relationships with midget bipolar axon terminals and midget ganglion cells. Furthermore we will investigate whether glycine and GABA are the neurotransmitters of these amacrine cells. 2) Since we can recognize the blue cone by morphological criteria we will determine wiring of blue cones to bipolar cells and investigate how the short wavelength channels differ from the two longer wavelength channels in their connectivity to ganglion cells. Other projects are proposed to 3) determine whether the midget ganglion cell to a single midget bipolar relationship is maintained outside of foveal retina and to, 4) look at the circuitry underlying rod (scotopic) pathways in the human and see how they interact with cone (photopic) pathways. 5) Finally, we will use EM immunocytochemistry to look at chemically different amacrine cell inputs to human and cat ganglion cell types and study the synaptology of the human dopaminergic cell system. Altogether, we propose comparative anatomical studies between cat and human retina, basing our investigations in human retina on the knowledge gained from functional morphological studies of the cat retina of the last decade and continuing into the future.